CVE-2026-33131

GET /admin/sensitive-data HTTP/1.1 Host: localhost:3000/abchehe? User-Agent: PoC-Client/1.0 # Description: Sending a request to a protected route. # The middleware checks event.url.pathname. # Due to the Host header containing extra path segments ('/abchehe?'), # the middleware logic fails to identify the route as '/admin/sensitive-data'. # The router, however, matches the request line ('GET /admin/sensitive-data') successfully. # Result: Authentication middleware bypassed.

{"cve": {"id": "CVE-2026-33131", "sourceIdentifier": "[email protected]", "published": "2026-03-20T11:18:02.700", "lastModified": "2026-03-20T19:45:14.473", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "H3 is a minimal H(TTP) framework. Versions 2.0.0-0 through 2.0.1-rc.14 contain a Host header spoofing vulnerability in the NodeRequestUrl (which extends FastURL) which allows middleware bypass. When event.url, event.url.hostname, or event.url._url is accessed, such as in a logging middleware, the _url getter constructs a URL from untrusted data, including the user-controlled Host header. Because H3's router resolves the route handler before middleware runs, an attacker can supply a crafted Host header (e.g., Host: localhost:3000/abchehe?) to make the middleware path check fail while the route handler still matches, effectively bypassing authentication or authorization middleware. This affects any application built on H3 (including Nitro/Nuxt) that accesses event.url properties in middleware guarding sensitive routes. The issue requires an immediate fix to prevent FastURL.href from being constructed with unsanitized, attacker-controlled input. Version 2.0.1-rc.15 contains a patch for this issue."}, {"lang": "es", "value": "H3 es un framework H(TTP) mínimo. Las versiones 2.0.0-0 hasta 2.0.1-rc.14 contienen una vulnerabilidad de suplantación de encabezado Host en NodeRequestUrl (que extiende FastURL) que permite el bypass de middleware. Cuando se accede a event.url, event.url.hostname, o event.url._url, como en un middleware de registro, el gestor de acceso _url construye una URL a partir de datos no confiables, incluyendo el encabezado Host controlado por el usuario. Debido a que el router de H3 resuelve el gestor de ruta antes de que se ejecute el middleware, un atacante puede proporcionar un encabezado Host manipulado (p. ej., Host: localhost:3000/abchehe?) para hacer que la verificación de ruta del middleware falle mientras el gestor de ruta aún coincide, eludiendo efectivamente el middleware de autenticación o autorización. Esto afecta a cualquier aplicación construida sobre H3 (incluyendo Nitro/Nuxt) que acceda a las propiedades de event.url en middleware que protege rutas sensibles. El problema requiere una solución inmediata para evitar que FastURL.href se construya con entrada no saneada y controlada por el atacante. La versión 2.0.1-rc.15 contiene un parche para este problema."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 7.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 5.2}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-290"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.0:*:*:*:*:node.js:*:*", "matchCriteriaId": "A80DE960-665D-4590-B6D5-645099B808E2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc10:*:*:*:node.js:*:*", "matchCriteriaId": "603A08FC-B20B-4693-90A1-0BF5F08B43AC"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc11:*:*:*:node.js:*:*", "matchCriteriaId": "BCC5ECF0-0EED-48BC-95FA-1D2671A971A9"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc12:*:*:*:node.js:*:*", "matchCriteriaId": "BCCBE75E-DCF6-45FD-B57E-F8E2ADE3129F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc13:*:*:*:node.js:*:*", "matchCriteriaId": "3B66082C-3F3E-4BC6-9543-A2F9CFE3AAC6"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc14:*:*:*:node.js:*:*", "matchCriteriaId": "3D1C9D7B-3CE4-427B-93B4-EAF867159AFB"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc2:*:*:*:node.js:*:*", "matchCriteriaId": "C5E7779A-00CA-45E7-8F68-1DAB5388ED4A"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc3:*:*:*:node.js:*:*", "matchCriteriaId": "064C21F5-8633-45F3-9A3D-3FB029A867B9"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc4:*:*:*:node.js:*:*", "matchCriteriaId": "DDBC1DFD-8063-4AE1-92D8-B3B33735FEF0"}, {"vulnerable": true, "criteria": "cpe:2.3:a:h3:h3:2.0.1:rc5:*:*:*:node.js:* ... (truncated)